CPT codes are the standardized language used to report medical services to payers, ensuring accurate reimbursement for healthcare providers. For laboratory testing, the CPT code identifies the specific analysis performed for billing. Carbon dioxide testing, which usually measures total carbon dioxide or bicarbonate, is a common indicator of a patient’s electrolyte and acid-base balance. The appropriate code depends on whether the test is ordered alone or as part of a larger group of analyses.
Standalone Measurement of Total Carbon Dioxide
When Total Carbon Dioxide (bicarbonate) is ordered as the only test, the specific single CPT code used is CPT 82374. This code represents the chemical analysis of carbon dioxide, typically performed on a venous blood sample. The test measures all forms of carbon dioxide in the blood, primarily bicarbonate (\(\text{HCO}_3\)), which manages the body’s acid-base equilibrium.
However, CPT 82374 is rarely reported alone in clinical practice. The total carbon dioxide level is generally more useful when considered alongside other electrolytes, making it far more common for the test to be included within a pre-defined panel of related analyses.
Reporting Carbon Dioxide Through Metabolic Panels
Carbon dioxide testing is overwhelmingly performed as part of a bundled laboratory panel. These panels are pre-set groups of medically related tests frequently ordered together. When a panel code is reported, it covers all component tests, and the individual standalone code (CPT 82374) is not reported separately.
The two most common panels including total carbon dioxide are the Basic Metabolic Panel (BMP) and the Comprehensive Metabolic Panel (CMP).
Basic Metabolic Panel (BMP)
The BMP is reported using CPT 80048 and includes eight separate tests. This panel provides a snapshot of the patient’s kidney function, blood sugar, and fluid and electrolyte status.
The eight components are:
- Glucose
- Calcium
- Sodium
- Potassium
- Chloride
- Carbon dioxide
- Blood urea nitrogen (BUN)
- Creatinine
Comprehensive Metabolic Panel (CMP)
The CMP is an expanded version of the BMP, reported with CPT 80053. It includes all tests in the BMP, plus six additional tests evaluating liver function and protein levels.
The six additional tests are:
- Total protein
- Albumin
- Bilirubin
- Alkaline phosphatase (ALP)
- Alanine aminotransferase (ALT)
- Aspartate aminotransferase (AST)
Using CPT 80048 or CPT 80053 streamlines the process, billing all related tests under a single code. Since these panels are frequently used to assess general health, they are the typical way a carbon dioxide test is officially reported.
Coding Differences for Arterial Blood Gas Analysis
The partial pressure of carbon dioxide (\(\text{pCO}_2\)) is measured as part of an Arterial Blood Gas (ABG) test, which uses different CPT codes. The ABG requires blood drawn from an artery, a more complex procedure than the venous draw used for metabolic panels. This test measures the pressure of gases dissolved in the blood, providing immediate information on lung function and carbon dioxide removal.
The primary CPT code for a basic ABG analysis measuring \(\text{pH}\), \(\text{pCO}_2\), and \(\text{pO}_2\) is CPT 82803. CPT 82805 is used if the analysis includes measured oxygen saturation. The \(\text{pCO}_2\) result evaluates a patient’s respiratory status and ventilation.
This measurement is clinically separate from the Total \(\text{CO}_2\) (bicarbonate) test included in metabolic panels. Total \(\text{CO}_2\) is a chemical measurement of the bicarbonate buffer system, whereas \(\text{pCO}_2\) from an ABG is a direct gas measurement. The ABG is generally used in acute settings to assess acid-base disturbances and oxygenation. The different CPT codes reflect these differences in specimen source, testing methodology, and clinical application.